Disaster mitigation on lands affected by landslides in Banjarnegara Regency

Landslide mitigation on potentially-affected lands is one of the crucial efforts in Banjarnegara Regency. Such effort, however, must comply with the existing environmental and land use conditions. This research aimed to determine the landslide susceptibility level and landslide mitigation on the affected land. A descriptive quantitative method was used to determine landslide susceptibility, and a survey method was used to determine its condition. Landslide susceptibility was examined using an overlay analysis of the major factors: slope, texture fault, regolith, and geology. The analysis results show that the levels of landslide susceptibility of the research location consisted of: not prone (19.21%), slightly prone (4.95%), moderate (6.92%), prone (29.20%), and very prone (39.72%). It also predicted that 335,940 people (36.80%) lived in highly and very-highly vulnerable areas. Based on the results, mitigation is targeted on three groups of land, including water bodies (269.57 ha), vegetated area (69,946.98 ha), and non-vegetated area (3,506.25 ha). Both physical and social mitigation actions are thus required. Physical mitigation includes slope protection (terracing, vetiver system, slope-protection structures, ground fractures covering), water management (manual horizontal drainage, drainage channel), vegetation management (multi-stratum canopy, root morphology, and plant biomass), whereas social mitigation involves community management by promoting public awareness and vigilance against disasters, and the active role of both community and stakeholders.

STUDY OF RESIDUAL SOIL SLOPE STABILITY WITH THE APPLICATION OF HORIZONTAL DRAINAGE

This study determines the effectiveness of horizontal drains on a slope which refers to a landslide at Putrajaya, Malaysia, in 2007. The incident buried 27 cars, and about 1200 people were transferred to a safe place. The main cause was identified as continuous and heavy rainfall. In Malaysia, abundant rainfall is common during the wet season. Therefore, one of the remedial measures to improve slope stability is applying horizontal drain to flush out rising groundwater and increase soil strength. In this study, the finite element method package, Plaxis, is used to analyze the slope stability changes in terms of the factor of safety (FOS). The simulation of slope behavior includes the horizontal drain conditions in lowering the groundwater level based on three parameters: the heights, appropriate depth, and inclination angle. The horizontal drains are installed at four different heights of 1 m, 2 m, 8 m, and 28 m from the toe of the slope. Based on the results, the horizontal drain is most efficient to be installed with 15 m long and zero degrees angle at the height of 1 m from the toe of the slope. At 2 m height, the drain should be installed with 26 m long and an angle of 1.8 degrees, and at 8 m height, the drain should be installed with 12 m long and an angle of 4.8 degrees. Moreover, at 28 m, the horizontal drain should be installed 20 m long and at an angle of 8.5 degrees. Therefore, this paper highlights the exceedingly appropriate design of horizontal drains at different heights, lengths, and tilt angles along the slope surface.

The Helical Anchor Type with Application as a Horizontal Drainage Equipment for Slope Protection

Helical anchors, sometimes referred to as screw anchors, screw piles, and helical piles, are a steel screw-in piling and ground anchoring system used for building deep foundations. Screw piles are manufactured using varying sizes of tubular hollow sections for the pile or anchor shaft. This paper presents an innovation of the helical anchor for horizontal drains, a form of subsurface drainage systems for slope protection. To address the adverse effect of groundwater, an expansion of the application of the helical anchor structure in civil engineering is needed, and new drainage solutions are being considered. The features of the helical anchor type for horizontal drainage equipment, analyses of some of its advantages, and conditions of application are presented. Generally, a helical anchor for horizontal drainage is convenient for installation, maintenance, or removal, and is effective for both horizontal drainage and for anchoring the revetment. It is also a typical construction in drainage works, generally performed by a cranking handle or a rotary-percussion-type drilling machine. The helical anchor pipe for horizontal drainage has many segments with joints using a cranking hand for installation and is quite effective where the installation space is narrow or there is no machine. In particular, the installation of this equipment differs significantly from other drilling methods because it can be driven into a sand layer without a hole wall.

Hydrodynamic model of the formation of horizontal drainage runoff on drainless and slightly drained irrigated lands in the dry steppe zone of Ukraine

The article presents the results of the research, which are the basis of making a hydrodynamic model of the formation of drainage runoff of closed horizontal drainage on drainless and slightly drained irrigated lands in the dry steppe zone of Ukraine. The relevance of the research is in their need when designing the systems of horizontal drainage, determining drain spacing, modes of operation and the evaluation of drainage efficiency during its operation when irrigating with the use of modern sprinklers from a closed farm network. The objective of the research is to develop a generalized hydrodynamic model of formation of closed horizontal drainage runoff when irrigating from a closed farm network on drainless and slightly drained lands, which are typical for the watershed plains and coastal lowlands of the dry steppe zone of Ukraine. The task of the research to determine the basic conditions and factors of formation of horizontal drainage runoff, to specify the structure of groundwater inflow to the drains when having optimal drain spacing in the closed farm network and to define the prospects and areas of further research. Research methods and techniques: long-term (1975-2020) field experiments on drained areas with different drain spacing in typical hydrogeological conditions for watersheds and coastal lowlands; water balance studies; theoretical research methods (analysis and synthesis, comparison, generalization, zoning); to determine the structure of groundwater inflow to the drains, the method of electrohydrodynamic analogies when using the laboratory integrator EGDA 9/60 was applied. As a result of the research it was determined that in the conditions of a closed water farm network it is possible to increase drain spacing from 120-220 m to 240-400 m. When studying all the conditions of drainless and slightly drained watershed plains and coastal lowlands, the main sources forming the regime of groundwater and drainage runoff are the precipitation of 420 mm or 55.0% of water input, irrigation water - 340 mm or 45.0%, including 266 mm or 35,0% from irrigation and 75 mm or 10,0% from filtration from the canals. The analysis of the hydrodynamic model of drainage runoff formation shows that when having drain spacing as 240-400 m, the inflow from the zone located above the bottom of the drain is 2.6-4.8% of the total inflow to the drain. The ascending flow under the bottom of the drain enters it at an average angle of 600 and in all variants of drain spacing is 95.2-97.2% of the total inflow. When drain spacing increases from 240 to 300-400 m, the horizontal inflow from the area located below the bottom of the drain decreases with a corresponding increase in the ascending flow under the bottom of the drain. The average width of the ascending flow to the drain at the edge of the active zone of groundwater (9.0-10.0 m below the drain) is 13.0-20.0 m. The resulting model complements the existing theoretical and methodological knowledge base for designing horizontal drainage and is necessary in perspective researches on the formation of expert systems for optimization of the parameters and modes of irrigation and drainage functioning when applying modern broadcast sprinkler equipment irrigating from the closed farm network.

Reducing the Level of Groundwater In The City of Fergana

This paper discusses the current effects of groundwater levels on buildings and engineering communications in Fergana and ways to overcome them. The paper considers methods of lowering the groundwater level in the territory of the city of Fergana, using closed horizontal drainage and given hydrological calculations.

Construction of closed horizontal drainage on irrigated lands and determination of its parameters

The article describes the construction technology of closed horizontal drainage in irrigated areas, presents the results of theoretical studies to determine the depth of drainage, the width of the drainage trench, the diameter of the drainage pipe, the thickness of the filter material, the distance between the drains and the drainage module. According to the results of theoretical studies, the average drainage depth is 1.5 m, the width of the drainage trench is 0.3 m, the diameter of the drainage pipe is 0.1 m, the thickness of the filtration material is 0.1 m. The distance between the drains is 150 m with the drainage module 0.1 l/s, the distance between drains is 180 m with a drain module of 0.12 l/s, and the distance between drains is 210 m with a drain module of 0.14 l/s.

ADVANCED METHOD FOR CLEANING HORIZONTAL CLOSED DRAIN

The article discusses an advanced method for cleaning closed horizontal drainage systems in the irrigation zone. The technological process of cleaning from sediment is carried out by dragging winches of a special cable with a ruff, previously laid inside the horizontal closed drainage during primary cleaning with the help of the PDT-200 machine, through adjustable and fixed blocks. While the ruff has the ability to deviate and rotate along the longitudinal axis of the drainage pipe, and the mounting frames are installed in the inspection wells, fixed with bolts and sequentially re-installed from one well to another. The use of this method allows you to reduce the labor intensity, reduce the number of expensive reclamation machines used, special hoses and pumping equipment, as well as the use of manual labor and the consumption of a large amount of water. The improved method will significantly increase the productivity, quality and reliability of the technological process by eliminating the shortcomings in the spring and autumn cleaning of closed horizontal drainage. The effectiveness of the improved method is to increase the productivity and quality of cleaning the closed horizontal drainage from sediments, as well as to a sharp decrease in the level of mineralized groundwater.

ПЕРСПЕКТИВЫ РАЗВИТИЯ ДРЕНАЖНЫХ СИСТЕМ В НЕЧЕРНОЗЕМНОЙ ЗОНЕ РФ

В статье выполнена оценка состояния осушительных систем в Нечерноземной зоне РФ. К настоящему времени, построенный до 90-го года прошлого столетия закрытый горизонтальный дренаж практически полностью вышел из строя как по причине отсутствия надлежащего ухода и эксплуатации, так и выработки своего ресурса и требует незамедлительного проведения реконструкции или нового строительства. На основе анализа мирового и отечественного опыта даны основные направления развития дренажных систем, включающие совершенствование конструкции дрены, обеспечивающей предотвращение заиления, заохривания и зарастания корнями, и создание саморегулирующих и управляемых дренажных систем.The paper devoted to the research of the conditions of the drainage systems in the Non-Chernozem zone of the Russian Federation. Nowadays the underground horizontal drainage built before the 90s last century, has almost completely damaged or deteriorated because of unproper maintenance and operation. On the other hand, drainage obsolescence is observed so its reconstruction or construction of new one is required. World and domestic experience analysis resulted in the development of the main directions of drainage systems improvement, including design of the drainage system, which prevents silting, overgrowing by crop roots, and provides to create self-regulating and managing drainage systems.